1. Field of the Invention
The invention pertains to transaxle brakes for small transmissions and particularly pertains to an automatic brake adjustment for such transmissions to compensate for wearing of the brake engaging elements.
2. Description of the Related Art
Transmissions for small vehicles such as riding lawn mowers often include a brake disc which is rotated by one of the shafts of the transaxle. Braking of the rotation of such discs serves to brake the drive train movement of the associated gearing and such braking occurs through the movement of friction shoes or pucks which engage the brake disc under the operation of a pivoted lever. A transmission of this general type using a disc brake system is shown in U.S. Pat. No. 4,966,574. A similar braking system for small transmissions constituting an improvement of the above cited patent is disclosed in U.S. Pat. No. 5,195,386. The disclosures of both of these patents are incorporated into this application by reference.
In the braking systems disclosed in the aforementioned patents, the brake disc is frictionally engaged by pucks engaging opposite sides of the disc upon a brake lever being rotated in a braking direction. The brake disc is axially movable a limited degree upon its supporting shaft, and a cam arrangement defined on the brake lever, through operating pins, forces the brake puck on one side of the disc against the disc axially translating the disc against the opposing friction puck to apply a braking action to the disc from both disc sides.
The axial position of the brake lever on its supporting shaft is determined by a nut threaded upon the brake lever shaft and as the friction pucks wear, it is possible to compensate for this wear by manually rotating the brake lever nut to translate the brake lever toward the brake disc whereby an effective braking action will be produced during the normal operating range of the brake lever. The brake lever is usually connected to a foot operated brake pedal, and as the friction pucks wear, greater foot pedal movement is required to produce braking.
While it is possible to compensate for the wear occurring in the friction pucks by periodically tightening the nut on the brake lever shaft, such adjustments are often neglected due to ignorance on the part of the operator and the fact that the unskilled operator does not understand that the brake lever positioning nut needs to be adjusted as the friction material on the pucks is consumed. Accordingly, the necessary maintenance of the braking system is ignored and the transmission brake disc is not properly retarded when the brake pedal is operated, and with riding lawn mowers, it is not uncommon to have ineffective braking due to friction shoe or puck wear which produces a hazardous safety situation.